MAINE

Potato Breeding Program

2006 Progress Report

2006 Field Screening for Powdery Scab Resistance

Aroostook Research Farm

59 Houlton Road

Presque Isle, ME 04769

MAINE POTATO BREEDING PROGRAM

2006 ANNUAL PROGRESS REPORT

EXECUTIVE SUMMARY

The Maine Potato Breeding program is the only program in the northeast that has focused its objective to the development and selection of processing-type potatoes particularly for fries. Statistics show that majority of the total production in the state for the last five years were utilized as processed potatoes. The program supports the increasing demand for processed potatoes by the growing processing industry in Maine by developing and selecting new varieties that are suitable for fries and other frozen potato products. It also selects for varieties that are suitable for chips, as table-type and as specialty-colored potatoes.

Another major objective which is the development and selection of resistant potato varieties supports the sustainability of potato production in Maine and the whole of the eastern region. The breeding program continuously selects not only resistant varieties but also focuses on the “more durable type of resistance” and aims to incorporate “multiple resistances" to all its developed and selected clones recommended becoming varieties. Resistance to major diseases including late blight, Verticillium wilt, common and powdery scabs, Rhizoctonia and viruses are the priorities. In 2006, new crosses were made to incorporate insect resistances into the breeding populations using clones with trichomes and high foliar glycoalkaloids as mechanisms of resistance. Host plant resistance is still the most economical and sustainable approach to the control of potato pests and diseases. The use of resistant varieties could significantly reduce the use of harmful and costly pesticides used by growers resulting to lower cost of production and better profit.

Maine potatoes are marketed either as seeds, table or processing potatoes throughout the northeast states. Hence, it is important to identify clones which are adapted and acceptable in these areas. The coordinated NE-1014 regional trial conducted by the different collaborators saves time and resources since data are obtained by each state and made available to the breeder, enabling her to better judge breeding materials resulting to a better selection. In 2006 significant amount of germplasm (early and advanced materials) were distributed to the different collaborators in the eastern region in the US and Canada. The program regularly sends selections from the 20-hills observational trials and selected advanced promising clones to NY, NJ, PA, FL, VA and NC, which also evaluates clones from the single-hill selections.

In 2006 a promising table-type clone AF 1758-7 with potential of becoming a variety was tested in growers’ field in semi-commercial scale. An old clone, AF 875-x continues to perform well in Quebec, Canada. Its yield and chipping quality are good and has shown some degree of resistance to common scab. Certified seeds were produced this year for large-scale commercial planting in 2007.

This year’s advanced selections for the long russet types include: AF 2413-4, AF 2426-1 and AF 2431-2 Other selected advanced clones evaluated the same year from the advanced trials include long russet/white: AF 2199-6, AF 2280-5, AF 2412-2, AF 2413-4, AF 2497-2; round whites – AF 2115-1, AF 2172-56, AF 2215-1, AF 2291-10, AF 2321-4, AF 2322-2 AF 2376-5 and specialty round red- AF 2393-7 and round russet AF 2931-1.

SUMMARY OF RESULTS AND ACTIVITIES

Development, evaluation and selection of new genotypes.

The Maine breeding program produced about 271,188 true seeds from crosses between progenitors with high yield, good processing traits and multiple disease resistances (with late blight and common scab as high priority); including insect resistances using clones with good trichome traits and high foliar TGA. About 29,100 tubers were produced in the greenhouse and 22,455 single hills were planted in the field resulting in 295 (3.52%) selections. “B”seedling tubers of some crosses were sent to Idaho (~3,000 tubers) and Wisconsin (~2,300 tubers) breeding programs for evaluation. Promising selections from the different stages of evaluation are as follows: 26 (36%) long russet clones from the72 entries in 8-hill plots; 45 (35%) round white/red clones from the 127 entries from the 12-hill plots; and 38 (44.7%) clones out of the 85 entries planted in the 20-hills observational trial. Different yield trials were conducted: preliminary (42 entries), intermediate (24 entries); advanced yield trial I - 14 entries for long russets and 31 entries for round white/red types; advanced yield trial II - 17 entries for long russets and 25 entries for round white/red types. Certified seeds of the 15 most advanced promising clones were produced for next year’s trials.

Screening for resistance to economically important potato pests in Maine.

Disease screening under field conditions were conducted as follows: potato virus Y 99 entries) common scab set (30 and 85 entries for set 1 & 2, respectively), early and late blight (27 entries), PLRV (40 entries), Verticillium wilt (30 entries), powdery scab (17 entries) were conducted at the Aroostook Farm. All screenings was artificially inoculated except for the early/late blight trial which was naturally-infected with late blight during the later part of the growing season. Initial laboratory screening using a detached-leaf method and tuber inoculation were conducted in the laboratory for all clones and varieties used in the hybridization for late blight resistance to develop a base population with durable resistance to this important disease.

Multi-location evaluation of promising clones.

Selected clones were evaluated in the different states (Michigan, Wisconsin, Idaho, Minnesota) and in Quebec and Ontario, Canada. One chipping clone, AF 2211-9 was evaluated in the SFA trials around the country. Some advanced selections were sent to the national late blight evaluation trials and the scab national trials conducted at different locations in the country. Some were also sent to Wisconsin for disease screening and storage evaluation.